title: Plasminogen-stimulated airway smooth muscle cell proliferation is mediated by urokinase and annexin A2, involving plasmin-activated cell signalling.
abstract: OBJECTIVE
  The conversion of plasminogen into plasmin by interstitial urokinase plasminogen activator (uPA) is potentially important in asthma pathophysiology. In this study, the effect of uPA-mediated plasminogen activation on airway smooth muscle (ASM) cell proliferation was investigated.
  
  
  METHODS
  Human ASM cells were incubated with plasminogen (0.5-50 μg·mL(-1) ) or plasmin (0.5-50 mU·mL(-1) ) in the presence of pharmacological inhibitors, including UK122, an inhibitor of uPA. Proliferation was assessed by increases in cell number or MTT reduction after 48 h incubation with plasmin(ogen), and by earlier increases in [(3) H]-thymidine incorporation and cyclin D1 expression.
  
  
  RESULTS
  Plasminogen (5 μg·mL(-1) )-stimulated increases in cell proliferation were attenuated by UK122 (10 μM) or by transfection with uPA gene-specific siRNA. Exogenous plasmin (5 mU·mL(-1) ) also stimulated increases in cell proliferation. Inhibition of plasmin-stimulated ERK1/2 or PI3K/Akt signalling attenuated plasmin-stimulated increases in ASM proliferation. Furthermore, pharmacological inhibition of cell signalling mediated by the EGF receptor, a receptor trans-activated by plasmin, also reduced plasmin(ogen)-stimulated cell proliferation. Knock down of annexin A2, which has dual roles in both plasminogen activation and plasmin-signal transduction, also attenuated ASM cell proliferation following incubation with either plasminogen or plasmin.
  
  
  CONCLUSIONS
  Plasminogen stimulates ASM cell proliferation in a manner mediated by uPA and involving multiple signalling pathways downstream of plasmin. Targeting mediators of plasminogen-evoked ASM responses, such as uPA or annexin A2, may be useful in the treatment of asthma.
authors.affiliation: Department of Pharmacology, University of Melbourne, Parkville, VIC, Australia; Lung Health Research Centre, University of Melbourne, Parkville, VIC, Australia.
authors.forename: A G
authors.initials: AG
authors.lastname: Stewart
authors.forename: Y C
authors.initials: YC
authors.lastname: Xia
authors.forename: T
authors.initials: T
authors.lastname: Harris
authors.forename: S
authors.initials: S
authors.lastname: Royce
authors.forename: J A
authors.initials: JA
authors.lastname: Hamilton
authors.forename: M
authors.initials: M
authors.lastname: Schuliga
mesh_terms: D017306:Annexin A2 / Q000235:genetics / Q000378:metabolism*; D001980:Bronchi / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D019938:Cyclin D1 / Q000378:metabolism; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D005341:Fibrinolysin / Q000378:metabolism*; D006801:Humans; D006965:Hyperplasia; D009130:Muscle, Smooth / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology; D058539:Phosphatidylinositol 3-Kinase / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010958:Plasminogen / Q000378:metabolism*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000378:metabolism; D034622:RNA Interference; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors; D014162:Transfection; D014568:Urokinase-Type Plasminogen Activator / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
chemical_list: C472822:ANXA2 protein, human; D017306:Annexin A2; C530104:CCND1 protein, human; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors; D015842:Serine Proteinase Inhibitors; D019938:Cyclin D1; D010958:Plasminogen; D058539:Phosphatidylinositol 3-Kinase; C512478:EGFR protein, human; D066246:ErbB Receptors; D051057:Proto-Oncogene Proteins c-akt; D048049:Extracellular Signal-Regulated MAP Kinases; D005341:Fibrinolysin; D014568:Urokinase-Type Plasminogen Activator
keywords: EGF; airway wall remodelling; annexin A2 hetero-tetramer; asthma; plasmin; α2-antiplasmin